Also during the holiday season, I made this apple crisp a few times, and each time it turned out great. Once, however, I made it with a dairy-free substitute instead of butter, and rolled oats instead of quick oats, and it wasn't quite as good.
There's really nothing complicated about gluten-free apple crisp. You just have to make sure you use gluten-free oats and a gluten-free flour blend in place of all-purpose wheat flour. Since there's no pastry or dough of any kind, you don't need to worry about details like xanthun gum to thicken and bind. (Although the flour blend I use happens to contain some xanthun gum, I doubt it has any effect on the crumble topping.) So, if you have a favorite recipe already, just go with it.
This is the recipe I use, which I've adjusted to my liking. It's sweet, but not too sweet, and has a little lemon juice added for tartness. On different occasions, I've used Fuji, Honey Crisp, or Granny Smith apples. (Granny Smith are pretty tart, so you can probably leave out the lemon juice if you use those.) Once I even threw in a pear because I was short one apple.
Sometimes I make my own gluten-free flour blend, but my favorite pre-made one is Namaste Foods Perfect Flour Blend. It recently became available at Costco in a 5-pound bag, and it's much more affordable than the same product (in a smaller bag) at either my local natural foods store or what the people in my area call the "gluten-free store."
Gluten-Free Apple Crisp PRINTABLE RECIPE
6 apples - peeled, cored, and sliced
2 tsp lemon juice
2 Tbsp white sugar
1/2 tsp ground cinnamon
3/4 cup brown sugar
1 cup gluten-free oats (I use Bob's Red Mill Quick-Cooking Oats)
1/2 cup gluten-free flour blend (I use Namaste Foods Perfect Flour Blend)
1 tsp ground cinnamon
1/2 cup cold butter - cut into small pieces
1. Pre-heat oven to 350°.
2. Toss apples with lemon juice, white sugar, and 1/2 tsp cinnamon. Pour into a 9-inch square baking dish.
3. In a separate bowl, mix brown sugar, oats, GF flour, and 1 tsp cinnamon. Use a pastry cutter or fork to mash the cold butter into the oat-flour mixture until it resembles coarse crumbs. Spread over the apples to the edges of the dish and pat gently until even.
4. Bake for about 45 minutes or until the topping is golden brown and the sides are bubbling.